New Delhi, Aug 22: As uncertainty loomed large over Indo-Pak NSA talks, moderate Hurriyat Conference leader Bilal Lone and Shabir Shah were among four separatist leaders detained today at Delhi airport to prevent them from meeting Pakistan's NSA Sartaj Aziz in the event of his arrival here.

All the four separatist leaders were put under house arrest in the capital, official sources said.

Lone, who is the executive member of moderate faction of Hurriyat led by Mirwaiz Umer Farooq, was stopped at the ladder of the aircraft as he deplaned and was informed that he was under detention and would remain confined to his rented accommodation in South Delhi, the sources said.

Lone is the fourth separatist leader from Kashmir who was detained at the Delhi airport. Earlier, Shabir Shah, who broke away from Hurriyat last year and formed his Democratic Freedom Party, was detained along with two senior members of his party in the morning.

Bilal refused to make any comments about his detention. The separatist leaders were told that "restrictions have been imposed on their movement in the national capital" ahead a possible talks between Aziz and his Indian counterpart Ajit Doval, official sources said.

Shah along with two other separatist leaders Mohammed Abdullah Tari and Zamir Ahmed Sheikh are under house arrest in a south Delhi guest house and the trio will remain confined to that place only.

All the separatist leaders have been given an option that they were free only to travel to Srinagar, in case they wanted to. While leaving Srinagar, Shah had said the he would like to meet Aziz.

"Today we are going to ask the people of India whether former Indian Prime Minister A B Vajpayee, their leader LK Advani or Manmohan Singh were wrong. During their tenure, they never blocked us from meeting Pakistani officials when they came to India...

"Kashmir is an important issue...Pakistan's stand is clear. They are saying that they will come for talks and present whatever they want to say. India can also put forward its argument but Kashmir issue must be included," he insisted.

The top separatist leaders have received an invite from Pakistan High Commission in Delhi for a reception being hosted for Aziz, who is scheduled to arrive in Delhi tomorrow afternoon to hold talks with Doval on Monday if everything goes as per plans.

The Pakistan High Commission's invitation to hardliner Syed Ali Shah Geelani and other separatist leaders to meet Aziz has upset New Delhi but Pakistan has stuck to the line that such meetings were "routine".